W. Choi, Yeon Baek Seong, Tae Hoon Lee, Changhyun Park, Jin Wook Lee, M. Kim, N. Park, T. Lee
Extended Abstract Recently, energy shortages are appearing constantly. Therefore, the research on alternative energy has demanded [12]. In this study, the catalytic activity of Rh-based supported catalysts was investigated for the auto-thermal reforming of diesel oil. The auto-thermal reforming of diesel oil occur the chemical reaction of steam, oxygen and the vaporized diesel gas, and it was performed at high temperature condition above at 800 °C. Therefore, the catalytic activity can decrease by the sintering and the carbon coking. However, auto-thermal reforming has been considered as the appropriate method for diesel reforming, because auto-thermal reforming has showed less coke formation than other reforming method [2-5]. In this study, rhodium was used as the main active material for the production of hydrogen and the catalytic promoter was used alumina, zirconia, and ceria. Zirconia and ceria has been used as the catalytic promoter due to its high thermal stability and carbon coking resistibility. The Al-Ce-Zr based catalytic support material coated over metal foam plate was formed to the morphology of nano-structure. It was confirmed by XRD analysis that cerium and zirconium components in Al-Ce-Zr based catalytic support material was synthesized to CeZrO2 crystal structure. It was concluded that CeZrO2 prevents carbon deposition on catalyst active site due to their high lattice oxygen mobility. Carbon deposition is one of catalytic deactivation in hydrocarbons reforming reaction. The yield of hydrogen by diesel auto-thermal reforming increased with increasing reaction temperature, and was obtained 5, 15 and 43% at 600, 700 and 800 °C, respectively. The fuel conversions at same conditions were 20, 85 and 100%. The high hydrogen yield was obtained at 2.5 of steam/carbon ratio when reforming reaction was carried out at 800. The optimum condition of oxygen/carbon was also confirmed to 0.25. In this study, long-term activity test of Rh/AlCe-Zr based catalyst was carried out under the optimum auto-thermal reforming condition. The composition of hydrogen and carbon monoxide in dry product gas was maintained to approximately 45% and 11% during 500 h, respectively. The theoretical composition of syn-gas, which is calculated by material balance under same condition, was 56%. Therefore, it was concluded that the catalytic activity of Rh/Al-Ce-Zr based catalysts is very excellent on diesel auto-thermal reforming. The carbon content on the surface of catalysts after 100, 200, 300, 400and 500 h reactions was investigated by EDX analysis and the carbon deposition was not observed. It was also confirmed by TEM analysis that the crystal size of catalytic support materials increased with increasing reaction time. It was concluded that the change of crystal size is occurred by the sintering of alumina and the crystallization of CeZrO2 at high temperature condition. However, catalytic deactivation by the change of crystal structure was not observed for 500 h
{"title":"Longevity Tests of Rh/Al-Ce-Zr Catalyst for Auto-thermal Reforming of Diesel Oil","authors":"W. Choi, Yeon Baek Seong, Tae Hoon Lee, Changhyun Park, Jin Wook Lee, M. Kim, N. Park, T. Lee","doi":"10.11159/ICNNFC16.111","DOIUrl":"https://doi.org/10.11159/ICNNFC16.111","url":null,"abstract":"Extended Abstract Recently, energy shortages are appearing constantly. Therefore, the research on alternative energy has demanded [12]. In this study, the catalytic activity of Rh-based supported catalysts was investigated for the auto-thermal reforming of diesel oil. The auto-thermal reforming of diesel oil occur the chemical reaction of steam, oxygen and the vaporized diesel gas, and it was performed at high temperature condition above at 800 °C. Therefore, the catalytic activity can decrease by the sintering and the carbon coking. However, auto-thermal reforming has been considered as the appropriate method for diesel reforming, because auto-thermal reforming has showed less coke formation than other reforming method [2-5]. In this study, rhodium was used as the main active material for the production of hydrogen and the catalytic promoter was used alumina, zirconia, and ceria. Zirconia and ceria has been used as the catalytic promoter due to its high thermal stability and carbon coking resistibility. The Al-Ce-Zr based catalytic support material coated over metal foam plate was formed to the morphology of nano-structure. It was confirmed by XRD analysis that cerium and zirconium components in Al-Ce-Zr based catalytic support material was synthesized to CeZrO2 crystal structure. It was concluded that CeZrO2 prevents carbon deposition on catalyst active site due to their high lattice oxygen mobility. Carbon deposition is one of catalytic deactivation in hydrocarbons reforming reaction. The yield of hydrogen by diesel auto-thermal reforming increased with increasing reaction temperature, and was obtained 5, 15 and 43% at 600, 700 and 800 °C, respectively. The fuel conversions at same conditions were 20, 85 and 100%. The high hydrogen yield was obtained at 2.5 of steam/carbon ratio when reforming reaction was carried out at 800. The optimum condition of oxygen/carbon was also confirmed to 0.25. In this study, long-term activity test of Rh/AlCe-Zr based catalyst was carried out under the optimum auto-thermal reforming condition. The composition of hydrogen and carbon monoxide in dry product gas was maintained to approximately 45% and 11% during 500 h, respectively. The theoretical composition of syn-gas, which is calculated by material balance under same condition, was 56%. Therefore, it was concluded that the catalytic activity of Rh/Al-Ce-Zr based catalysts is very excellent on diesel auto-thermal reforming. The carbon content on the surface of catalysts after 100, 200, 300, 400and 500 h reactions was investigated by EDX analysis and the carbon deposition was not observed. It was also confirmed by TEM analysis that the crystal size of catalytic support materials increased with increasing reaction time. It was concluded that the change of crystal size is occurred by the sintering of alumina and the crystallization of CeZrO2 at high temperature condition. However, catalytic deactivation by the change of crystal structure was not observed for 500 h","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75252203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The size of the building blocks fundamentally governs physical performances of the macro-scale graphene based structures since larger building blocks usually yields better mechanical and electrical properties. Density gradient centrifugation method has emerged as a versatile and scalable method for sorting colloidal 2D nanomaterials. This paper provides a facile and effective size sorting approach to graphene oxide (GO) flakes with large sizes up to 40 μm. The GO flakes were dispersed within distilled water. The centrifugation process parameters were calculated with respect to specific size ranges of GO flakes. Scanning electron microscopy utilized to prove the effectiveness of the separation process. Image processing analysis showed GO flakes with specific size ranges can be separate from aqueous suspension by controlling rotational speed and centrifugation time. The process was performed by using common benchtop centrifuges with low intensity centrifugal fields which requires low investment for a scalable process.
{"title":"A Facile and Effective Method for Size Sorting of Large Flake Graphene Oxide","authors":"Ece Özçakır, V. Eskizeybek","doi":"10.11159/ICNNFC16.132","DOIUrl":"https://doi.org/10.11159/ICNNFC16.132","url":null,"abstract":"The size of the building blocks fundamentally governs physical performances of the macro-scale graphene based structures since larger building blocks usually yields better mechanical and electrical properties. Density gradient centrifugation method has emerged as a versatile and scalable method for sorting colloidal 2D nanomaterials. This paper provides a facile and effective size sorting approach to graphene oxide (GO) flakes with large sizes up to 40 μm. The GO flakes were dispersed within distilled water. The centrifugation process parameters were calculated with respect to specific size ranges of GO flakes. Scanning electron microscopy utilized to prove the effectiveness of the separation process. Image processing analysis showed GO flakes with specific size ranges can be separate from aqueous suspension by controlling rotational speed and centrifugation time. The process was performed by using common benchtop centrifuges with low intensity centrifugal fields which requires low investment for a scalable process.","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75224588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Structure Study of Mn Doped in SrTiO3 by X-ray Diffraction","authors":"Z. Booq, S. K. Alghaith","doi":"10.11159/ICNNFC16.121","DOIUrl":"https://doi.org/10.11159/ICNNFC16.121","url":null,"abstract":"","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77339066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Kamel, Z. Demerdash, H. El-Baz, S. Hassan, Faten Salah, W. Mansour, Olfat Hamamm
Extended Abstract Liver fibrosis is the wound-healing response of the liver to chronic injury it is very important to investigate different treatments and therapies for cirrhosis as the liver is one of the target organs for which stem cell-based therapeutics is very promising. In this study, Isolation, propagation, and characterization of unrestricted somatic stem cells (USSCs) from cord blood (CB) samples were performed and induced to differentiate into osteoblasts, adipocytes and hepatocyte-like cells. The therapeutic potentiality of USSCs in two experimental models of chronic liver injury was evaluated. First experimental model (30 mice): Ten Schistosoma mansoni infected mice were intravenously injected with USSCs 1×10 cell/mouse. Ten were infected untreated (pathological control) and 10 healthy mice (negative control). 2nd experimental model (30 hamsters): Twenty were injected with repeated doses of carbon tetrachloride Sigma-Aldrich Chemical Co. (St Louis, Missouri, USA) to induce liver fibrosis; 10 were treated with intrahepatic injection of 3x10 USSCs and the other 10 were untreated pathological control. Ten healthy hamsters served as negative control. Animals were sacrificed 12 weeks post transplantation, and their liver sections were examined for detection of human hepatocyte-like cells by immunohistochemical staining. Moreover, liver sections were examined for fibrosis levels. Sera of sacrificed animals were tested for liver functions. CB USSCs, with fibroblast-like morphology, expressed high levels of CD44, CD90, CD73 and CD105 and were negative for CD34, CD45, and HLA-DR. USSCs showed high expression of transcripts for Oct4 and Sox2 and were in vitro differentiated into osteoblasts, adipocytes, and hepatocyte-like cells. In both models transplantation of CBUSSCs resulted in engraftment of the fibrosed livers with newly formed hepatocytes evidenced by positive immunostaining with human Hep Par1, α-fetoprotein, CK-18, CK-7 and OV6. Transplanted liver sections showed diminished hepatic fibrosis with significantly lower fibrotic index as well as significantly improved liver functions compared to the pathological control (p<0.001). Conclusion These data provide hope that human CBderived USSCs are introduced as multipotent stem cells with great potentiality in regenerative medicine & strengthens the concept of cellular therapy for the treatment of liver fibrosis. This work is extracted from the project 1410 supported by the Science and Technology Development Funds (STDF), Cairo, Egypt.
{"title":"Implementation of Cord- Blood Derived Unrestricted Somatic Stem Cells in the Regeneration of two Experimental Models: Carbon Tetrachloride and S. Mansoni Induced Liver Fibrosis","authors":"M. Kamel, Z. Demerdash, H. El-Baz, S. Hassan, Faten Salah, W. Mansour, Olfat Hamamm","doi":"10.11159/NDDTE16.121","DOIUrl":"https://doi.org/10.11159/NDDTE16.121","url":null,"abstract":"Extended Abstract Liver fibrosis is the wound-healing response of the liver to chronic injury it is very important to investigate different treatments and therapies for cirrhosis as the liver is one of the target organs for which stem cell-based therapeutics is very promising. In this study, Isolation, propagation, and characterization of unrestricted somatic stem cells (USSCs) from cord blood (CB) samples were performed and induced to differentiate into osteoblasts, adipocytes and hepatocyte-like cells. The therapeutic potentiality of USSCs in two experimental models of chronic liver injury was evaluated. First experimental model (30 mice): Ten Schistosoma mansoni infected mice were intravenously injected with USSCs 1×10 cell/mouse. Ten were infected untreated (pathological control) and 10 healthy mice (negative control). 2nd experimental model (30 hamsters): Twenty were injected with repeated doses of carbon tetrachloride Sigma-Aldrich Chemical Co. (St Louis, Missouri, USA) to induce liver fibrosis; 10 were treated with intrahepatic injection of 3x10 USSCs and the other 10 were untreated pathological control. Ten healthy hamsters served as negative control. Animals were sacrificed 12 weeks post transplantation, and their liver sections were examined for detection of human hepatocyte-like cells by immunohistochemical staining. Moreover, liver sections were examined for fibrosis levels. Sera of sacrificed animals were tested for liver functions. CB USSCs, with fibroblast-like morphology, expressed high levels of CD44, CD90, CD73 and CD105 and were negative for CD34, CD45, and HLA-DR. USSCs showed high expression of transcripts for Oct4 and Sox2 and were in vitro differentiated into osteoblasts, adipocytes, and hepatocyte-like cells. In both models transplantation of CBUSSCs resulted in engraftment of the fibrosed livers with newly formed hepatocytes evidenced by positive immunostaining with human Hep Par1, α-fetoprotein, CK-18, CK-7 and OV6. Transplanted liver sections showed diminished hepatic fibrosis with significantly lower fibrotic index as well as significantly improved liver functions compared to the pathological control (p<0.001). Conclusion These data provide hope that human CBderived USSCs are introduced as multipotent stem cells with great potentiality in regenerative medicine & strengthens the concept of cellular therapy for the treatment of liver fibrosis. This work is extracted from the project 1410 supported by the Science and Technology Development Funds (STDF), Cairo, Egypt.","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88749407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Bertok, Dominika Pihíková, Alena Holazová, A. Hushegyi, Ľ. Kluková, J. Filip, S. Belicky, Erika Dosekova, P. Kasák, J. Tkáč
Extended Abstract Glycans are complex saccharide moieties covering all cell surfaces presented on different biomolecules. Almost 75% of all proteins are glycosylated, and these glycans can form thousands of different structures.[1] Moreover, these structures may slightly change during a specific disease progress – depending on the biomarker observed, there is a possibility to distinguish between healthy individuals and people suffering from a specific disease, mostly cancer (prostate cancer using PSA as a biomarker)[2] or autoimmune diseases (rheumatoid arthritis, system sclerosis observing IgG N-glycosylation).[3] Viral adhesion on cell surface and subsequent penetration is also dependent on the glycan epitopes present on a cell surface.[4, 5] Using nanoscale manipulation of biorecognition elements (antibodies, lectins as glycan-bindnig proteins or glycans) using self-assembled monolayers (SAMs) allowed to prepare highly sensitive, reproducible and robust biosensors for detection of various analytes – from glycoproteins and whole viral particles to intact cells. Moreover, using SAMs allows to control a biorecognition element s density, orientation and anti-fouling properties of our surfaces.[6] Using nanomaterials like gold nanoparticles of different size or graphene oxide flakes leads to improved characteristics of prepared devices – electrochemical and impedimetric biosensors in this case. Electrochemical devices, mainly in combination with different nanostructures, provide cheap, highly reliable and sensitive platform for glycomic analyses.[7] We present here a novel approach for a glycoprofilation of various analytes (antibodies, PSA, viral hemagglutinins and viruses and eukaryotic cell lines) using small, low cost, highly sensitive electrochemical devices based on different platforms compared to standardly used LC, CE or MS methods for the glycan analysis. Beside electrochemical impedance spectroscopy and voltammetry, other methods for the surface characterization were used (quartz crystal microbalance, surface plasmon resonance, atomic force and scanning electron microscopy and x-ray photoelectron spectroscopy) and our results were compared to outputs from other analytical methods (protein microarray, enzyme-linked lectin assay and MALDI-TOF MS).
聚糖是覆盖在不同生物分子上的所有细胞表面的复杂糖类基团。几乎75%的蛋白质都是糖基化的，这些糖基可以形成数千种不同的结构。[1]此外，在特定的疾病进展过程中，这些结构可能会发生轻微的变化，这取决于所观察到的生物标志物，有可能区分健康个体和患有特定疾病的人，主要是癌症(前列腺癌使用PSA作为生物标志物)[2]或自身免疫性疾病(类风湿关节炎，系统性硬化症观察IgG n -糖基化)[3]。病毒在细胞表面的粘附和随后的渗透也依赖于存在于细胞表面的聚糖表位。[4,5]利用自组装单层(SAMs)对生物识别元件(抗体、凝集素作为聚糖结合蛋白或聚糖)进行纳米级操作，可以制备高灵敏度、可重复性和健壮的生物传感器，用于检测各种分析物——从糖蛋白和整个病毒颗粒到完整的细胞。此外，使用sam可以控制生物识别元素的密度、方向和表面的防污性能。[6]使用纳米材料，如不同尺寸的金纳米颗粒或氧化石墨烯薄片，可以改善所制备器件的特性——在这种情况下是电化学和阻抗生物传感器。电化学装置主要与不同的纳米结构相结合，为糖糖分析提供了廉价、高可靠和敏感的平台。[7]我们在这里提出了一种新的方法，用于各种分析物(抗体，PSA，病毒血凝素和病毒以及真核细胞系)的糖谱分析，与标准使用的LC, CE或MS方法相比，使用基于不同平台的小型，低成本，高灵敏度的电化学设备进行糖谱分析。除了电化学阻抗谱和伏安法，我们还使用了其他表面表征方法(石英晶体微天平、表面等离子体共振、原子力、扫描电镜和x射线光电子能谱)，并将我们的结果与其他分析方法(蛋白质微阵列、酶联凝集素测定和MALDI-TOF质谱)的结果进行了比较。
{"title":"Novel Analysis of Glycan Structures: Nanoscale Approach","authors":"T. Bertok, Dominika Pihíková, Alena Holazová, A. Hushegyi, Ľ. Kluková, J. Filip, S. Belicky, Erika Dosekova, P. Kasák, J. Tkáč","doi":"10.11159/ICNB16.103","DOIUrl":"https://doi.org/10.11159/ICNB16.103","url":null,"abstract":"Extended Abstract Glycans are complex saccharide moieties covering all cell surfaces presented on different biomolecules. Almost 75% of all proteins are glycosylated, and these glycans can form thousands of different structures.[1] Moreover, these structures may slightly change during a specific disease progress – depending on the biomarker observed, there is a possibility to distinguish between healthy individuals and people suffering from a specific disease, mostly cancer (prostate cancer using PSA as a biomarker)[2] or autoimmune diseases (rheumatoid arthritis, system sclerosis observing IgG N-glycosylation).[3] Viral adhesion on cell surface and subsequent penetration is also dependent on the glycan epitopes present on a cell surface.[4, 5] Using nanoscale manipulation of biorecognition elements (antibodies, lectins as glycan-bindnig proteins or glycans) using self-assembled monolayers (SAMs) allowed to prepare highly sensitive, reproducible and robust biosensors for detection of various analytes – from glycoproteins and whole viral particles to intact cells. Moreover, using SAMs allows to control a biorecognition element s density, orientation and anti-fouling properties of our surfaces.[6] Using nanomaterials like gold nanoparticles of different size or graphene oxide flakes leads to improved characteristics of prepared devices – electrochemical and impedimetric biosensors in this case. Electrochemical devices, mainly in combination with different nanostructures, provide cheap, highly reliable and sensitive platform for glycomic analyses.[7] We present here a novel approach for a glycoprofilation of various analytes (antibodies, PSA, viral hemagglutinins and viruses and eukaryotic cell lines) using small, low cost, highly sensitive electrochemical devices based on different platforms compared to standardly used LC, CE or MS methods for the glycan analysis. Beside electrochemical impedance spectroscopy and voltammetry, other methods for the surface characterization were used (quartz crystal microbalance, surface plasmon resonance, atomic force and scanning electron microscopy and x-ray photoelectron spectroscopy) and our results were compared to outputs from other analytical methods (protein microarray, enzyme-linked lectin assay and MALDI-TOF MS).","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83175822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extended Abstract Objectives: We demonstrate a simple method for the synthesis of gold nanoparticles (Au NPs) via a boiling and refluxing methodology [1]. The proposed experiment also can help students to understand the factors involved in the stability of Au NPs by exploring the adsorption interaction between Au NPs and various substances [2]. Scope: The students in this study found that the surface plasmon resonance band of Au NP solutions underwent a redshift (i.e., from 520 to 650 nm) because of NaCl-induced aggregation caused by the elimination of the repulsive electrostatic force. In addition, a sufficient amount of bovine serum albumin molecules adsorbed on the surface of Au NPs through electrostatic interactions provides steric barriers that hinder electrolyte-induced aggregation. The surface properties of Au NPs are important in determining the aggregation of Au NPs. An optical sensor for Hg ions is developed by using 3-MPA-modified Au NPs (3-MPA-Au NPs) [3, 4]. If their aggregation was driven by the recognition and binding of metal ions, the color change would allow sensing of the ions by the naked eye. The experiment possesses several attractive features: the synthesis method circumvents the use of a surfactant or template; the selectivity and sensitivity experiments use small amounts of reagents; and the whole experiment can be carried out within 3 hrs. at room temperature. Results: In addition, this current teaching material also provides students with an introduction to major concepts of nanoscale science and engineering [5] including (i) size and scale, (ii) structure of matter, (iii) forces and interactions, (iv) self-assembly, (v) tools and instrumentation, and (vi) science, technology, and society. Hence, these teaching materials are suitable for incorporation into the undergraduate general chemistry laboratory curriculum. Students performed this experiment and improved their recognition of the nanoscale science and engineering concepts.
{"title":"Education of Nanoscience: Introduction to the Preparation, Characterization, and Application of Gold Nanoparticles","authors":"Yangming Lin","doi":"10.11159/ICNEI16.106","DOIUrl":"https://doi.org/10.11159/ICNEI16.106","url":null,"abstract":"Extended Abstract Objectives: We demonstrate a simple method for the synthesis of gold nanoparticles (Au NPs) via a boiling and refluxing methodology [1]. The proposed experiment also can help students to understand the factors involved in the stability of Au NPs by exploring the adsorption interaction between Au NPs and various substances [2]. Scope: The students in this study found that the surface plasmon resonance band of Au NP solutions underwent a redshift (i.e., from 520 to 650 nm) because of NaCl-induced aggregation caused by the elimination of the repulsive electrostatic force. In addition, a sufficient amount of bovine serum albumin molecules adsorbed on the surface of Au NPs through electrostatic interactions provides steric barriers that hinder electrolyte-induced aggregation. The surface properties of Au NPs are important in determining the aggregation of Au NPs. An optical sensor for Hg ions is developed by using 3-MPA-modified Au NPs (3-MPA-Au NPs) [3, 4]. If their aggregation was driven by the recognition and binding of metal ions, the color change would allow sensing of the ions by the naked eye. The experiment possesses several attractive features: the synthesis method circumvents the use of a surfactant or template; the selectivity and sensitivity experiments use small amounts of reagents; and the whole experiment can be carried out within 3 hrs. at room temperature. Results: In addition, this current teaching material also provides students with an introduction to major concepts of nanoscale science and engineering [5] including (i) size and scale, (ii) structure of matter, (iii) forces and interactions, (iv) self-assembly, (v) tools and instrumentation, and (vi) science, technology, and society. Hence, these teaching materials are suitable for incorporation into the undergraduate general chemistry laboratory curriculum. Students performed this experiment and improved their recognition of the nanoscale science and engineering concepts.","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87698432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extended Abstract One of many important applications of magnetic nanoparticles is the separation of complex mixture by magnetic field [1]. Magnetic nanoparticles aggregate with impurities of the mixture under magnetic field in the separation process. We have built a simple experimental setup for monitoring the temporal change of magnetic weight with a conventional electronic balance in order to study the agglomeration dynamics of magnetite nanoparticles by magnetic field [2]. The magnetic field is applied in the direction parallel to the gravitational force in our setup. Magnetite nanoparticles are prepared by reacting FeCl2 and FeCl3 in aqueous ammonia solution [3]. When the ferrofluid sample is placed under the field, the magnetic weight of the sample jumps instantaneously by Neel and Brown relaxation, and then increases slowly over a few days as the nanoparticles agglomerate. The slow increase of the magnetic weight shows the stretched exponential behaviour, M(t) = M() + [M(0) – M()] exp[-(t/) ] where 0 < < 1. The stretched exponential function results from the distribution of energy barrier involved in the dynamics, which can be calculated by the inverse Laplace transformation of the stretched exponential function if the Arrhenius pre-exponent factor of the rate constant is given [4]. Typical agglomeration of magnetite nanoparticles by magnetic field gives the energy barrier distribution function with the peak energy of ~36 kJ mol -1 and the width of ~8 kJ mol -1 [5]. In addition to the overall stretched exponential change, the magnetic weight of ferrofluid shows thermal fluctuation, which is explained well with the Boltzmann factor. The energy difference of < 10 kJ mol -1 , estimated from the temperature dependence of the dynamics, that is, the Boltzmann factor corresponds to the energy difference between the agglomerated states. Again, this energy difference is not a single value but shows some distribution.
{"title":"Dynamics of Agglomeration of Magnetite Nanoparticles under Magnetic Field Studied by Monitoring Magnetic Weight","authors":"D. Jin, Hackjin Kim","doi":"10.11159/ICNEI16.102","DOIUrl":"https://doi.org/10.11159/ICNEI16.102","url":null,"abstract":"Extended Abstract One of many important applications of magnetic nanoparticles is the separation of complex mixture by magnetic field [1]. Magnetic nanoparticles aggregate with impurities of the mixture under magnetic field in the separation process. We have built a simple experimental setup for monitoring the temporal change of magnetic weight with a conventional electronic balance in order to study the agglomeration dynamics of magnetite nanoparticles by magnetic field [2]. The magnetic field is applied in the direction parallel to the gravitational force in our setup. Magnetite nanoparticles are prepared by reacting FeCl2 and FeCl3 in aqueous ammonia solution [3]. When the ferrofluid sample is placed under the field, the magnetic weight of the sample jumps instantaneously by Neel and Brown relaxation, and then increases slowly over a few days as the nanoparticles agglomerate. The slow increase of the magnetic weight shows the stretched exponential behaviour, M(t) = M() + [M(0) – M()] exp[-(t/) ] where 0 < < 1. The stretched exponential function results from the distribution of energy barrier involved in the dynamics, which can be calculated by the inverse Laplace transformation of the stretched exponential function if the Arrhenius pre-exponent factor of the rate constant is given [4]. Typical agglomeration of magnetite nanoparticles by magnetic field gives the energy barrier distribution function with the peak energy of ~36 kJ mol -1 and the width of ~8 kJ mol -1 [5]. In addition to the overall stretched exponential change, the magnetic weight of ferrofluid shows thermal fluctuation, which is explained well with the Boltzmann factor. The energy difference of < 10 kJ mol -1 , estimated from the temperature dependence of the dynamics, that is, the Boltzmann factor corresponds to the energy difference between the agglomerated states. Again, this energy difference is not a single value but shows some distribution.","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81977664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extended Abstract Memristive switching in oxide semiconductors relies on the formation and disruption of conductive nano-filaments [1]. This effect is considered promising for the next generation of non-volatile memories. Yet, the switching event is a complicated electronic and ionic process, which may involve more than one mechanism. In order to elucidate the switching mechanism, advanced microscopy investigations proved challenging because of heavily dependence of the results on specimen preparation techniques. Important information can be obtained if switching leads to a macroscopic change of nonelectrical properties, for instance magnetic properties. In this respect, n-type Mn-ZnO and p-type NiO provide a unique testbeds since the magnetic properties of these oxides are strongly dependent on the distribution of oxygen vacancies [2]. We show that resistive switching in n-type ferromagnetic Mn-ZnO and p-type antiferromagnetic NiO coexists with a switching of the magnetic phase. Thin films of these oxides were sandwiched between two metallic electrodes and resistive switching was induced. Nano-devices were patterned out of the trilayers by resorting to electron beam lithography and physical etching. We found that a switching of the resistance corresponds to a switching of the magnetic phase in the film [3, 4]. By measuring the magnetic properties of the devices in the two resistive states, we can draw important conclusions on the underlying switching mechanism. For instance, in Mn-ZnO the effect is not filamentary type and occurs uniformly under the interface, whereas in NiO the effect is filamentary type. By measuring the change of magnetic properties we could exclude that switching was due to the formation of Ni-ion filaments across the device. We have demonstrated [4] that the switching is due to the formation and rapture of oxygen-vacancy filaments.
{"title":"Revealing the Nature of Nano-filaments in Memristive Oxide Memories","authors":"Xiaolei Wang, Q. Shao, A. Ruotolo","doi":"10.11159/ICNNFC16.102","DOIUrl":"https://doi.org/10.11159/ICNNFC16.102","url":null,"abstract":"Extended Abstract Memristive switching in oxide semiconductors relies on the formation and disruption of conductive nano-filaments [1]. This effect is considered promising for the next generation of non-volatile memories. Yet, the switching event is a complicated electronic and ionic process, which may involve more than one mechanism. In order to elucidate the switching mechanism, advanced microscopy investigations proved challenging because of heavily dependence of the results on specimen preparation techniques. Important information can be obtained if switching leads to a macroscopic change of nonelectrical properties, for instance magnetic properties. In this respect, n-type Mn-ZnO and p-type NiO provide a unique testbeds since the magnetic properties of these oxides are strongly dependent on the distribution of oxygen vacancies [2]. We show that resistive switching in n-type ferromagnetic Mn-ZnO and p-type antiferromagnetic NiO coexists with a switching of the magnetic phase. Thin films of these oxides were sandwiched between two metallic electrodes and resistive switching was induced. Nano-devices were patterned out of the trilayers by resorting to electron beam lithography and physical etching. We found that a switching of the resistance corresponds to a switching of the magnetic phase in the film [3, 4]. By measuring the magnetic properties of the devices in the two resistive states, we can draw important conclusions on the underlying switching mechanism. For instance, in Mn-ZnO the effect is not filamentary type and occurs uniformly under the interface, whereas in NiO the effect is filamentary type. By measuring the change of magnetic properties we could exclude that switching was due to the formation of Ni-ion filaments across the device. We have demonstrated [4] that the switching is due to the formation and rapture of oxygen-vacancy filaments.","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86690297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extended Abstract The mass is one of the basic biophysical parameters describing the properties of biological systems. It is inherently connected to many important intracellular biophysical processes like protein expression or cell division [1]. Only few experimental methods can determine mass of a single cell, however most of them obtain their results indirectly by determining the cell volume and approximating the density of the cell. Microcantilever-based biosensor method allows us to determine the mass of an adherent cell in a direct and non-destructive way. Additionally, the measurement is label–free it does not require any external markers or fluorescent labels as compared to other methods. In this work, we determined the average value of the mass of single cell of brewer yeast Saccharomyces cerevisiae using the dynamic mode of 8-cantilever arrays CLA500-070-08V Cantisens system (ConcentrisSwitzerland). Microcantilever-based sensor uses a laser based optical system to determine the oscillation frequency or bending amplitude of microcantilever. Laser light illuminates the free tip of the cantilever and Position Sensitive Detector (PSD) determines the position of reflected light [2]. Then the PSD signal is used to determine the bending amplitude or resonance frequency of the cantilever excited by the piezoelectric element. The general idea of cantilever-based sensors was born before 1970, but the huge potential of this method was explored only in last few decades, when the sensor miniaturization technology was fully developed. Microcantilever-based methods were then expanded to other research areas like biology, biotechnology, chemistry and physics. They were employed to measure with high precision and sensitivity various material and environmental parameters like viscosity, temperature, density, flow velocity or reaction energy. Yeast cells are eukaryotic microorganisms classified as members of the fungus kingdom. Yeasts cells typically measure several micrometres in diameter. We chose them because S. cerevisiae are simple eukaryotic cells, serving as a model for all eukaryotes. Furthermore, yeast cells are easy to culture and are resistant to environment conditions like dehydration. They also have a simple shape which allowed us to observe and count them using optical and confocal microscopies. The yeast strain used in this study is mainly used in the production of alcohol. Cell mass determination is based on resonance frequency shift between loaded (with yeast cells attached) and unloaded cantilever [3]. The measurements were performed in the fundamental mode of resonance frequency. We measured the decrease in the value of the resonance frequency related to the increase of cantilever’s weight in each measurement. The optical and confocal microscopies were employed to determine the position of each cell on cantilever surface which was crucial for a precise calculation of single cell mass. We determined it to be (47,6± 1,1) pg. The results sh
{"title":"Single Cell Mass Measurement with Microcantilever Biosensor","authors":"Bogdan Łabędź, A. Wańczyk, Z. Rajfur","doi":"10.11159/ICNNFC16.122","DOIUrl":"https://doi.org/10.11159/ICNNFC16.122","url":null,"abstract":"Extended Abstract The mass is one of the basic biophysical parameters describing the properties of biological systems. It is inherently connected to many important intracellular biophysical processes like protein expression or cell division [1]. Only few experimental methods can determine mass of a single cell, however most of them obtain their results indirectly by determining the cell volume and approximating the density of the cell. Microcantilever-based biosensor method allows us to determine the mass of an adherent cell in a direct and non-destructive way. Additionally, the measurement is label–free it does not require any external markers or fluorescent labels as compared to other methods. In this work, we determined the average value of the mass of single cell of brewer yeast Saccharomyces cerevisiae using the dynamic mode of 8-cantilever arrays CLA500-070-08V Cantisens system (ConcentrisSwitzerland). Microcantilever-based sensor uses a laser based optical system to determine the oscillation frequency or bending amplitude of microcantilever. Laser light illuminates the free tip of the cantilever and Position Sensitive Detector (PSD) determines the position of reflected light [2]. Then the PSD signal is used to determine the bending amplitude or resonance frequency of the cantilever excited by the piezoelectric element. The general idea of cantilever-based sensors was born before 1970, but the huge potential of this method was explored only in last few decades, when the sensor miniaturization technology was fully developed. Microcantilever-based methods were then expanded to other research areas like biology, biotechnology, chemistry and physics. They were employed to measure with high precision and sensitivity various material and environmental parameters like viscosity, temperature, density, flow velocity or reaction energy. Yeast cells are eukaryotic microorganisms classified as members of the fungus kingdom. Yeasts cells typically measure several micrometres in diameter. We chose them because S. cerevisiae are simple eukaryotic cells, serving as a model for all eukaryotes. Furthermore, yeast cells are easy to culture and are resistant to environment conditions like dehydration. They also have a simple shape which allowed us to observe and count them using optical and confocal microscopies. The yeast strain used in this study is mainly used in the production of alcohol. Cell mass determination is based on resonance frequency shift between loaded (with yeast cells attached) and unloaded cantilever [3]. The measurements were performed in the fundamental mode of resonance frequency. We measured the decrease in the value of the resonance frequency related to the increase of cantilever’s weight in each measurement. The optical and confocal microscopies were employed to determine the position of each cell on cantilever surface which was crucial for a precise calculation of single cell mass. We determined it to be (47,6± 1,1) pg. The results sh","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89865271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Skládal, J. Přibyl, V. Horňáková, P. Gereg, Z. Fohlerova, D. Kovář, M. Pešl
{"title":"Biosensing with AFM","authors":"P. Skládal, J. Přibyl, V. Horňáková, P. Gereg, Z. Fohlerova, D. Kovář, M. Pešl","doi":"10.11159/ICNB16.1","DOIUrl":"https://doi.org/10.11159/ICNB16.1","url":null,"abstract":"","PeriodicalId":31009,"journal":{"name":"RAN","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84779873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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